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Biomedical subjects

C Marco

Publications and source records attributed to C Marco.

At least 37 records · Page 2Linked to original sources
PubMed1996

Evidence of differential effects produced by ethanol on specific phospholipid biosynthetic pathways in rat hepatocytes.

1. The aim of the present study was to investigate the effects of ethanol in vitro on the phospholipid biosynthetic pathways in hepatocytes isolated from the rat. We have used [methyl-14C]-choline, [1-3H]-ethanolamine and L-[3-3H]-serine as exogenous precursors of the corresponding phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS). 2. Incubation of hepatocytes in the presence of ethanol significantly alters the incorporation of radiolabel from [14C]-choline and [3H]-ethanolamine into the metabolic intermediates and the final products of the CDP-choline and CDP-ethanolamine pathways. Radioactivity in the metabolic intermediates of both pathways was significantly decreased and the amount of label in PE was reduced whilst that of PC was not modified. 3. In the presence of 4-methylpyrazole, an inhibitor of alcohol dehydrogenase (ADH) activity, ethanol produces a reduction in the label of choline phosphate, ethanolamine phosphate and a significant decrease in the amount of PC and PE radiolabel. 4. On the other hand, ethanol increases the incorporation of serine into phosphatidylserine, phosphatidylethanolamine and phosphatidylcholine, although this effect is observed only in the absence of 4-methylpyrazole, indicating that this alteration is produced by some metabolite generated as a consequence of hepatic alcohol metabolism. 5. Ethanol also interferes with the methylation of phosphatidylethanolamine produced via the CDP-ethanolamine pathway but it does not alter phosphatidylethanolamine methylation when this phospholipid is produced by mitochondrial phosphatidylserine decarboxylation, suggesting the existence of different intramembrane pools of phosphatidylethanolamine, which may exhibit different sensitivity to alcohol. 6. Our results indicate that ethanol exerts two different effects on phospholipid metabolism in hepatocytes: a stimulatory effect on the incorporation of exogenous substrates into different phospholipids probably related to an alteration in the availability of lipogenic substrates as a consequence of ethanol metabolism, and another inhibitory effect produced by ethanol per se, which can be observed only when ethanol metabolism is inhibited by the presence of a specific inhibitor of alcohol dehydrogenase activity.

Alcohol Dehydrogenase↗
PubMed1996

Responses of leptin to short-term fasting and refeeding in humans: a link with ketogenesis but not ketones themselves.

We investigated the response of leptin to short-term fasting and refeeding in humans. A mild decline in subcutaneous adipocyte ob gene mRNA and a marked fall in serum leptin were observed after 36 and 60 h of fasting. The dynamics of the leptin decline and rise were further substantiated in a 6-day study consisting of a 36-h baseline period, followed by 36-h fast, and a subsequent refeeding with normal diet. Leptin began a steady decline from the baseline values after 12 h of fasting, reaching a nadir at 36 h. The subsequent restoration of normal food intake was associated with a prompt leptin rise and a return to baseline values 24 h later. When responses of leptin to fasting and refeeding were compared with that of glucose, insulin, fatty acids, and ketones, a reverse relationship between leptin and beta-OH-butyrate was found. Consequently, we tested whether the reciprocal responses represented a causal relationship between leptin and beta-OH-butyrate. Small amounts of infused glucose equal to the estimated contribution of gluconeogenesis, which was sufficient to prevent rise in ketogenesis, also prevented a fall in leptin. The infusion of beta-OH-butyrate to produce hyperketonemia of the same magnitude as after a 36-h fast had no effect on leptin. The study indicates that one of the adaptive physiological responses to fasting is a fall in serum leptin. Although the mediator that brings about this effect remains unknown, it appears to be neither insulin nor ketones.

3-Hydroxybutyric Acid↗
PubMed1996

[Endorectal echography. Its usefulness in the study of neoplasms of the rectum].

OBJECTIVE: To analyze prospectively the results of the first endorectal ultrasonographies performed at the Coloproctology Unit of the Hospital Mutua de Terrassa in patients with rectal tumors. METHODS: During the period between September 94 to June 95, 27 endorectal ultrasonographies were performed to patients with rectal tumors. The echographies were performed with a 360 degrees transducer. The ultrasound findings were compared to the histological results. RESULTS: Three patients were not treated surgically, and were excluded from the analysis. In addition, three patients with perianastomotic recurrence were excluded. Of the remaining 21 patients the level of penetration in the rectal wall was correctly identified in 17 (81%). The presence of metastatic nodes was correctly assessed in 19 of the 24 patients explored (78%). CONCLUSION: For the preoperative assessment of rectal tumors, endorectal ultrasonography offers a good accuracy even during the learning curve.

Adult↗
PubMed1995

Persistence of the effects of ethanol in vitro on the lipid order and enzyme activities of chick-liver membranes.

Results demonstrate for the first time that ethanol exerts two different effects on the lipid order of chick-liver mitochondria and microsomes: a fluidizing effect both in the core and at the surface of the membrane, which depends on its physical presence, and a rigidization of the surface of these membranes which occurs after its removal. In addition, and directly related to the reduction in fluidity produced in the membrane surface after ethanol removal, we have detected a persistent alteration in different enzyme activities involved in the hepatic mitochondrial and microsomal electron-transport systems. The persistence of the alterations in the lipid order and enzyme activities may result from a structural rearrangement of the lipid and protein components produced in the lipid bilayer surface when ethanol is no longer present in the membrane.

Animals↗
PubMed1995

[The endoscopic treatment of postcholecystectomy biliary leakage].

Although there is a decrease in the total number of complications observed on performance of laparoscopy cholecystectomy (LC) there does appear to be an increase in biliary tract lesions. Seven cases of postcholecystectomy biliary leakage treated with endoscopic methods are presented. These cases include 4 patients with leakage from the cystic canal stump and 3 with leakage from the common bile duct. In 5 cases the biliary tract lesion occurred following LC, 1 after conventional cholecystectomy and in 1 reconverted LP. CPRE identified the site of the leakage in the 7 patients and in 2 residual choledocholithiasis. In 5 cases treatment consisted in endoscopic papillotomy and placement of biliary endoprosthesis while only papillotomy was performed in 2 patients. In one of these cases CPRE was repeated and the sphincterotomy widened due to persistence of the leakage at 5 days, with the same finally closing at 15 days of the second CPRE. Closure of the biliary leakage was obtained in the other 6 cases in less than 72 hours post-CPRE. No complications secondary to the technique were observed. It was concluded that CPRE together with endoscopic papillotomy and placement of biliary prostheses is an effective and safe treatment for postcholecystectomy biliary leakages of the common bile duct or cystic duct.

Aged↗
PubMed1993

Hydatid disease of the soft tissues of the lower limb: findings in three cases.

Three cases of hydatid disease are reported, all presenting as soft tissue lesions in the lower extremities. All three cases were studied with ultrasound (US), two with computed tomography (CT), and two with magnetic resonance (MR) imaging techniques. Two patients presented with multivesicular lesions which were considered diagnostic of hydatid disease. The third patient showed a lesion with a predominantly solid pattern, closely mimicking a soft-tissue neoplasm. US was not diagnostic, but MR outlined vesicular structures and a fibrous pericyst. Hydatid disease presenting in the soft tissues can therefore be diagnosed with confidence when it shows multivesicular lesions but MR may be the most useful imaging technique when a complex or solid pattern is present.

Adult↗
PubMed1993

Cholesterol synthesis and esterification in isolated enterocytes: regulation by cholesterol and cholestyramine feeding.

The purpose of the present study was to investigate the physiological control of the main regulatory enzymes of cholesterol metabolism in isolated enterocytes obtained from chick duodenum, jejunum and ileum. Cholesterol feeding resulted in an inhibition of 3-hydroxy-3-methyl-glutaryl-CoA reductase and mevalonate 5-pyrophosphate decarboxylase, while cholestyramine feeding increased reductase activity in all the regions studied and decarboxylase activity only in duodenum. Cholesterol feeding markedly increased acyl-CoA:cholesterol acyltransferase, but the effects of cholestyramine were less clear. The effects on transferase activity cannot be due to differences in the availability of acyl-CoA as exogenous substrate as no significant differences were found in acyl-CoA hydrolase activity after any of the dietary treatments. The effects of cholesterol feeding were related to changes in the cholesterol content of epithelial cells, whereas in the case of cholestyramine this relationship was less apparent.

Animals↗
PubMed1992

Physical properties, lipid composition and enzyme activities of hepatic subcellular membranes from chick embryo after ethanol treatment.

Exposure of chick embryos to ethanol resulted in significant alterations to the lipid composition of various different hepatic subcellular membranes. A marked decrease in cholesterol levels and an increase in the phospholipid content of microsomes and mitochondria was observed. Ethanol also affected the fatty acid profiles, mainly by decreasing the percentage of oleic acid in phosphatidylcholine and phosphatidylethanolamine in the mitochondria and phosphatidylethanolamine in the microsomes. In spite of these changes ethanol only induced alterations in the fluidity of the mitochondrial membranes, which showed a more rigid core, in contrast to the phospholipid-head region, which was not affected. In accordance with the changes observed in the physical state of the membrane, the enzymes involved in the microsomal electron-transport systems were not modified by ethanol, while cytochrome oxidase activity decreased by 50% compared to the activity in the mitochondria from control chick embryos. These findings establish that during the chick-embryo developmental period the mitochondria are more sensitive to ethanol than are the microsomes.

Animals↗
PubMed1992

Comparative study of the effect of ethanol on the fluidity of subcellular hepatic membranes.

The aim of this study has been to compare the effects of chronic ethanol administration on the lipid composition and fluidity of chick-liver microsomes and mitochondria. Cholesterol levels were increased only in microsomal membranes whilst the fatty-acid profiles were considerably altered in the major phospholipids in both membranes. By using fluorescence polarization we found that ethanol produces a disorganisation of acyl chains in the core of microsomes and mitochondria and consequently causes higher fluidity. In addition, opposite changes were induced by ethanol in the polar region of the microsomes, inducing a more rigid area in the membrane.

Animals↗
PubMed1991

Ethanol and lipid metabolism. Differential effects on liver and brain microsomes.

We have determined the effect of prolonged ethanol treatment on several enzyme activities related to lipid metabolism in chick-brain and liver microsomes. Ethanol increased microsome cholesterol levels in both organs. The treatment caused a marked increase in the hepatic HMG-CoA reductase and ACAT activities while in the brain a clear decrease was found in these enzyme activities. At the same time the activity of reacylation of phospholipids, was clearly modified in both brain and liver. Thus, while in the liver the turnover of acyl moieties of phosphatidylethanolamine, sphingomyelin and phosphatidylinositol was enhanced by ethanol consumption, in the brain only the reacylation of phosphatidylserine increased to any significant extent. These results indicate that ethanol exerts a differential action in brain and liver, namely cholesterol synthesis and esterification decreased in brain and increased in chick liver. Ethanol also induces faster phospholipid metabolism in both brain and liver microsomes.

Animals↗
PubMed1991

Is exocrine pancreatic cancer a hormone-dependent tumor? A study of the existence of sex hormone receptors in normal and neoplastic pancreas.

The 5-year survival rate of patients with exocrine pancreatic cancer after surgery is less than 5%, in patients treated with radical surgery, with or without adjuvant therapy. It has been well documented clinically and experimentally that sex hormones influence the physiology of the exocrine pancreas. Hormone manipulation inhibits the growth of human pancreatic cancer in nude mice. Several nonrandomized studies have suggested the efficacy of antihormone therapy in the treatment of advanced pancreatic cancer. However, the existence of sex hormone receptors in exocrine pancreatic cancer has been a matter of controversy. This study was designed to investigate the presence of sex hormone receptors (estrogens, progesterone and androgens in normal pancreas and exocrine pancreatic cancer, using two different methods: immunohistochemistry and enzyme immunoassay. Twenty-eight biopsies of normal pancreas and 15 biopsies of exocrine pancreatic cancer were studied. Estrogen receptors and progesterone receptors were measured by enzyme immunoassay, using specific monoclonal antibodies. Androgen receptors were determined by radioligand assay. Sixteen biopsies of normal pancreas and 12 biopsies of exocrine pancreatic cancer were studied by immunohistochemistry. In exocrine pancreatic cancer we could not detect estrogen receptors or progesterone receptors, either by enzyme immunoassay or immunohistochemistry. Androgen receptors were always negative (less than 2 fm/mg). In the normal pancreas, 5 out of 28 cases showed increased levels of progesterone receptors (greater than 10 fm/mg) as measured by enzyme immunoassay. Immunohistochemistry revealed progesterone receptors in the pancreatic islets of 16 normal pancreases studied. Nuclear staining was observed in more than 70% of the cells. Estrogen receptors were always negative by immunohistochemistry and enzyme immunoassay in the normal pancreas.2+n

Adenocarcinoma↗
PubMed1991

Influence of ethanol on liver and plasma lipid levels during chick embryo development.

Ethanol introduced into the air chamber of the egg during the last week of the chick embryonic period did not induce changes in liver or embryo weights. Alcohol dehydrogenase activity increased during the period studied in both ethanol and control groups, however, ethanol significantly inhibited the enzymatic activity. Alcohol administration did not alter plasma or liver cholesterol levels. On the other hand, three days after the beginning of the treatment, ethanol decreases plasma triglyceride levels increasing simultaneously the content of this lipid in the liver. If the ethanol treatment is continued for ten days the opposite occurs. An increase and decrease in liver and plasma triglycerides were observed respectively. These results suggest that ethanol interferes with processes which maintain plasmatic triglyceride levels.

Alcohol Dehydrogenase↗